Phased-array devices operate by splitting a coherent wave source (e.g. electromagnetic or acoustic) into multiple individual sub-beams, shifting the wave phase of the individual sub-beams, and then emitting the sub-beams in close, wavelength-scale, physical proximity relative to one another. This arrangement allows, through control of the relative phases of the individual sub-beams, the generation of engineered wavefronts. Such spatial phase control enables attributes such as solid-state beam steering and engineered depth projection.
Electromagnetic phased-array devices are well known for microwave systems and are becoming increasingly so for optical (infrared, visible, and ultraviolet) systems. A difficulty with conventional phased-array design is that there is typically an asymmetrical (e.g. linear) output power distribution proportional to the linear phase distribution of the output channels.
This asymmetrical power distribution can interfere with device functions, such as beam steering, which require accurate control of both phase and amplitude. In microwave systems, asymmetric power output can be mitigated by assigning a separate amplifier to each microwave channel. Such an approach can be difficult to unfeasible for optical systems, however.